pole star

noun2

1. •
   The star visible to the naked eye which was in the past, is now, or will be in the future nearest a celestial pole of a planet.

   • Polaris is currently the pole star of planet Earth.
2. •
   (figurative) A person, principle, or thing which acts as a guide; a guiding light; also, something which attracts much attention; a centre of attention.

   • But it [our hotel] has one great advantage for a stranger, by being in the market place, and the next neighbour of the huge church of St. Nicholas: […] A better pole-star could scarcely be desired. — 1817